This disclosure relates to a semiconductor device provided with a rewritable nonvolatile memory module, and more particularly, to a technology for facilitating evaluation of nonvolatile memory characteristics.
Semiconductor devices, such as microcontrollers, are used to control various types of electronic equipment and are employed in various products. Some semiconductor devices are provided with a rewritable nonvolatile memory, such as a flash memory. Reading data from, writing data to, and erasing data of the flash memory are performed in accordance with instructions from a processor. The miniaturization of semiconductor devices has complicated the control of write and erase operations to the flash memory. Therefore, evaluation of flash memory characteristics is essential at a prototyping stage of the flash memory, at a development stage of a micro control unit (MCU) with an internal flash memory, and at a manufacturing stage of these devices.
A technology for evaluating the characteristics of nonvolatile storage devices, like the flash memory, is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2007-34554 (Patent Document 1). The technology disclosed in Patent Document 1 relates to a semiconductor integrated circuit including a writable and erasable nonvolatile memory module and a central processing unit (CPU). According to the technology disclosed in Patent Document 1, the semiconductor integrated circuit has a first operation mode and a second operation mode. In the first operation mode, the CPU sequentially executes instructions to control write and erase operations to the nonvolatile memory module. In the second operation mode, a local CPU responds to a command issued by the CPU and sequentially executes instructions to control write and erase operations to the nonvolatile memory module. In normal operation of the semiconductor integrated circuit, the second operation mode allows the CPU to execute other processing tasks while the local CPU is performing write operation or other operations to the nonvolatile memory module, thereby achieving real-time processing. When the semiconductor integrated circuit conducts a test on the nonvolatile memory module, the semiconductor integrated circuit can select either of the first operation mode and second operation mode.